Semantic Sensor Network Incubator Group Charter

The mission of the Semantic Sensor Network Incubator Group, part of the Incubator Activity, is to begin the formal process of producing ontologies that define the capabilities of sensors and sensor networks, and to develop semantic annotations of a key language used by services based sensor networks.

Join the Semantic Sensor Network Incubator Group.

End date 3 September 2010
Confidentiality Proceedings are public
Initial Chairs Laurent Lefort, Amit Sheth and Kerry Taylor
Initiating Members
Usual Meeting Schedule Teleconferences: Every week
Face-to-face: Once Annually


As networks of sensors become more commonplace there is a greater need for the management and querying of these sensor networks to be assisted by standards and computer reasoning. The OGC's Sensor Web Enablement [1] activities have produced a services-based architecture and standards, including four languages for describing sensors, their capabilities and measurements, and other relevant aspects of environments involving multiple heterogeneous sensors. These standards assist, amongst other things, in cataloguing sensors and understanding the processes by which measurements are reached, as well as limited interoperability and data exchange based on XML and standardized tags. However, they do not provide semantic interoperability and do not provide a basis for reasoning that can ease development of advanced applications.

Ontologies and other semantic technologies can be key enabling technologies for sensor networks because they will improve semantic interoperability and intergration, as well as facilitate reasoning, classification and other types of assurance and automation not included in the OGC standards. A semantic sensor network will allow the network, its sensors and the resulting data to be organised, installed and managed, queried, understood and controlled through high-level specifications. Sensors are different to other technologies, such as service-oriented architecture, because of the event based nature of sensors and sensor networks and the temporal relationships that need to be considered. Further, when reasoning about sensors the various constraints, such as power restrictions, limited memory, variable data quality, and loosely connected networks need to be taken into account

The SSN-XG will work on two main objectives:

(a) the development of ontologies for describing sensors, and
(b) the extension of the Sensor Markup Language (SML), one of the four SWE languages, to support semantic annotations.

The first objective, ontologies for sensors, will provide a framework for describing sensors. These ontologies will allow classification and reasoning on the capabilities and measurements of sensors, provenance of measurements and may allow reasoning about individual sensors as well as reasoning about the connection of a number of sensors as a macroinstrument. The sensor ontologies will, to some degree, reflect the OGC standards and, given ontologies that can encode sensor descriptions, understanding how to map between the ontologies and OGC models is an important consideration. According to W3C recommendations [2], OWL-DL will be the preferred language for ontology specification. The SSN-XG will also investigate mapping between OGC standards and OWL specifications of sensors.

The second objective of semantic annotation of sensor descriptions and services that support sensor data exchange and sensor network management will a serve similar purpose as that espoused by semantic annotation of Web services. We will use as an input for this objective ongoing work on SML-S [3] which in turn borrows from the SAWSDL [4] (also a W3C recommendation) for semantic annotation of WSDL-based Web Services, and SA-REST for semantic annotation for RESTful services [5].

Success Criteria

The group will be successful if it produces the deliverables and encourages interest, collaboration, and discussion on ontologies, semantic annotation of SWE languages and related tools that will enable semantic sensor networks.

Out of Scope

Anything not explicitly listed as being in scope is out of scope.


The SSN-XG will maintain a wiki with relevant information such as a review of relevant ontologies (and application to sensor systems, if any) and research projects that have an interest in semantic sensor networks. It will deliver one report and make a W3C submission:


While there are no formal dependencies for this XG, a number of other activities are closely related. The most obvious is the Open Geospatial Consortium's activities in Sensor Web Enablement, including SensorML, which the work in this XG should be compatible with. The SSN-XG will include representatives from the OGC. There are also a number of other related projects and research groups, such as the Semantic Sensor Web project at Wright State University's Kno.e.sis center [6] that have investigated use of ontologies and semantic annotation of SWE languages. The SSN-XG intends that its wiki and review will list all the relevant projects and ontologies, and the SSN-XG will solicit and welcome input from any related projects that we become aware of during the SSN-XG.

External Groups

MMI Device Ontology development: http://marinemetadata.org/community/teams/ontdevices
Review and leverage existing work that has been done by the Marine Metadata Initiative


It is envisioned that the XG will have begin with 60-minute telecons every week at a time that provides an adequate compromise over the various time zones of the interested participants. This can be modified as the work proceeds. During the telecons, the participants will review work done by individuals and sub-groups, and new work items will be defined and assigned. Additionally, it may be useful to have periodic face-to-face meeting at a venue for which a significant number of XG participants are likely to attend.

Expected participation follows the W3C Process Document discussion of Good Standing


This group primarily conducts its work on the public mailing list public-xg-ssn@w3.org (archive) . The group's Member-only list is member-xg-ssn@w3.org (archive)

Information about the group (deliverables, participants, face-to-face meetings, teleconferences, etc.) is available from the Semantic Sensor Network Incubator Group home page.

Decision Policy

As explained in the Process Document (section 3.3), this group will seek to make decisions when there is consensus. When the Chair puts a question and observes dissent, after due consideration of different opinions, the Chair should record a decision (possibly after a formal vote) and any objections, and move on.

Patent Policy

This Incubator Group provides an opportunity to share perspectives on the topic addressed by this charter. W3C reminds Incubator Group participants of their obligation to comply with patent disclosure obligations as set out in Section 6 of the W3C Patent Policy. While the Incubator Group does not produce Recommendation-track documents, when Incubator Group participants review Recommendation-track specifications from Working Groups, the patent disclosure obligations do apply.

Incubator Groups have as a goal to produce work that can be implemented on a Royalty Free basis, as defined in the W3C Patent Policy.

For more information about disclosure obligations for this group, please see the W3C Patent Policy Implementation.

Additional Information

Sensor Markup Language

The OpenGIS® Sensor Model Language Encoding Standard (SensorML) specifies information models and XML encoding that provide a framework within which the geometric, dynamic, and observational characteristics of sensors and sensor systems can be defined. SensorML can be used to describe a sensor as well as the measurement processes associated with the sensor.

About this Charter

This charter for the Semantic Sensor Network Incubator Group has been created according to the Incubator Group Procedures documentation. In the event of a conflict between this document or the provisions of any charter and the W3C Process, the W3C Process shall take precedence.

Charter update history:

[1] OGC Sensor Web Enablement, http://www.opengeospatial.org/projects/groups/sensorweb, accessed Oct 10, 2008

[2] OWL Web Ontology Language, http://www.w3.org/TR/owl-guide/, accessed Oct. 10, 2008

[3] Amit Sheth, Cory Henson, and Satya Sahoo, "Semantic Sensor Web," IEEE Internet Computing, July/August 2008, p. 78-83. http://doi.ieeecomputersociety.org/10.1109/MIC.2008.8

[4] Semantic Annotations for WSDL and XML Schemans, http://www.w3.org/2002/ws/sawsdl/spec/, accessed Oct. 10, 2008

[5] SA-REST, http://wiki.knoesis.org/index.php/SA-REST, accessed Oct. 10, 2008

[6] Semantic Sensor Web, http://knoesis.wright.edu/research/semsci/application_domain/sem_sensor/, accessed Oct. 10, 2008

Michael Compton and Amit Sheth

$Date: 2010/05/21 14:20:40 $